“In the 13th century, Rome’s population was around 20,000. At the height of the Roman Empire, it had been over a million — so those 20,000 Romans were living amid the ruins of a city built for 50 times as many people.

In a way, that was good for posterity. The Roman monuments we’re familiar with today — the Colosseum, the Forum, the temples — were not knocked down and built over, but simply left empty, slowly crumbling into ruin. A few did remain in use, perhaps turned to new purposes — for example the Pantheon, a temple to ‘all the gods’ built by Emperor Hadrian, had been turned into a Christian church. Others were stripped of their ‘pagan’ decorations, or even cannibalised for building stone for new construction.

However, there was little new construction in the Middle Ages. Rome has many notable buildings from the days of the Caesars, and many from the Renaissance onwards; but few traces remain of the intervening period.

The great city walls, built by Emperor Aurelian in 271-75 CE, remained intact as the city’s primary defence — though since their circuit was 19 km long, there was no way the city’s shrunken population could hope to defend them against a serious assault. Their purpose was primarily one of prestige. Much of the space within the walls was overgrown rubble that had reverted to grassland, with only scattered ruins of the larger buildings, and comparatively small pockets of habitation.

The aqueducts which had brought fresh water to classical Rome’s vast population were no longer functional, destroyed in Justinian’s futile and destructive attempt to reconquer Italy in the 6th century.

Much of the mediaeval population lived on the west bank of the Tiber, in the area called Trastevere. In Roman times it had been a suburb where the wealthy built their villas, but during the Middle Ages it had become a crowded area of narrow, unpaved streets where people of all social ranks lived — including Rome’s Jewish community. In 1555 a later Pope would order that the Jews be segregated inside a walled ghetto, but in the 13th century they were still allowed to live alongside the Christians. In 1170 it was reported that around 200 Jews lived in Rome: 1% of the city’s total population.

It should be noted that while Rome in the 13th century had lost 98% of its population compared to the 1st century, 20,000 inhabitants was still quite a respectable size by mediaeval standards. There were bigger cities — Florence, Venice and Genoa all had over 100,000 people, and Milan closer to 200,000; but in the whole of the British Isles, for example, there was only one city (London) larger than Rome in the year 1200. A foreigner visiting Rome for the first time would still consider it a big and bustling city; but the extent of the ruins and the vast circumference of the walls was mute evidence that once it was larger still.

Rome’s primary source of income was the Catholic Church. Not only did the Papacy collect revenues from all over Europe, some of which were naturally spent within the city, but pilgrims came from all over to visit the Eternal City: its churches and historical sites connected to early Christianity such as the graves of the martyrs. In effect, Rome was one of the world’s first tourist destinations. It was said that Rome had one church for every day of the year — in fact that is an underestimate, as a list from the 14th century gives the names of 414 churches within the city.

The Pope was the secular ruler of the city of Rome and the surrounding region, as well as the head of the Catholic Church. However, Rome also had many influential aristocratic families such as the Orsini, Savelli, Annibaldi and Colonna, who were ambitious for power. They resented the efforts of the Pope to control them — at least, when they were not scheming to have one of their own kinsfolk elected to the throne of St Peter.

During the previous century, Rome had experimented with a republican form of government, with a Senate of 56 members elected by the city’s citizens (members of the merchant and artisan class). The popes had opposed this development by force; and Pope Lucius II bears the dubious distinction of being possibly the only Pope to have been killed in battle, leading his army in a failed attempt to recapture Rome from its own citizens. However, the Commune of Rome and the Senate eventually collapsed, and the Papacy reasserted its authority. By the start of the 13th century there was still an elected Senator — just one — but he was effectively a city manager or mayor, subordinate to the Pope. However, the citizens of Rome were well aware of the glorious imperial past of their city, and appeals to their civic pride could still be potent.

The political rivalries, both between the Pope and the aristocracy and between opposing noble factions, led to many confrontations, and sometimes open fighting in the streets of Rome. Noble clans had their own small private armies of retainers, and often built fortified manor-houses for themselves within the city, noticeable for their tall towers which were a symbol of family pride and power. These towers were a prominent feature of many Italian cities in this era. There were over a hundred of them in Rome alone by the mid 13th century.

Despite all the trouble, visitors from all over Europe continued to flock to the Eternal City. An English traveller, Master Gregory of Oxford, came to the city just before 1200 and wrote an account of his visit which was preserved as a kind of guidebook. He spoke of Rome’s ‘forest of towers’, of the great monuments of ancient times standing tall amid the smaller modern buildings, or isolated in empty grassland, of the vast walls with their countless towers and gates.

He also rhapsodised about the smaller beauties; the carvings and statues that could still be found here and there amid the ruins, for which he felt a fascination that was almost magical (magica quaedam persuasio, in his words).”